One type of prior art load support vibration isolation mount which is used for vehicle engine mounts, for example, comprises elastically deformable hard rubber cushions or the like for cushioning the transfer of vibrations as between the engine and the vehicle frame. In the application of the mount to a vehicle, such solid elastically deformable engine mounts do help isolate the vehicle body frame carrying the engine from engine induced mechanical vibration and the engine from vehicle induced vibrations. However, such mounts suffer from disadvantages in that they are unable to attenuate the wide range of mechanical vibrations experienced in use on an automobile. For example, an automobile is designed to operate under many speed, torque, acceleration and deceleration conditions, all of which create different mechanical vibration force, frequency and amplitude patterns. The above-mentioned conventional shock absorber type engine mounts are preset and passive in that they only passively react to vibration forces based on their preset elastic design characteristics. Such vibration isolation mounts can be designed to operate quite well over certain narrow mechanical vibration patterns. However, because of their design they are not effective to attenuate vibrations over all operating ranges of the engine and vehicle.
Certain other prior art mounts, such as vehicle engine mounts, utilize a closed fluid shock absorber system for cushioning the transfer of vibrations between the engine and vehicle frame. Since these fluid shock absorber mounts are closed systems, the mounts act much like the elastically deformable spring or hard rubber cushion mounts discussed above. Further, in cases of large relative movement between the parts being supported, the shock attenuation substantially diminishes as the fluid pressure rises. Although certain shock absorber mounts provide for multiple fluid chambers and different flow paths depending upon the relative displacement of the parts being supported, such systems are very complex and costly to construct and are also ultimately limited by the total volume and fluid accommodating space in the overall closed system at an individual shock absorber mount.
The above-mentioned prior art mounts thus permit an unacceptable level of transfer of vibration forces between the engine and vehicle frame or between other parts being supported, and/or involve very complicated, expensive and space wasting constructions. There is a need for an improved load support vibration isolation mount which has enhanced energy absorbing ability in response to dynamic loading, which has a broader response to different frequencies of dynamic loading as compared with the aforementioned known mounts, and which at the same time is relatively simple and economical.